Measurements of the earth's gravitational acceleration, and measurements of differences in the earth's gravitational acceleration between different depths in the earth, can be useful in determining the bulk density (or specific gravity) of various earth formations, among other applications. More particularly, measurements of gravity difference between two positions or depths may be used to determine whether the formation is primarily oil, water or gas filled at various depths and geographic locations in the earth.
Accelerometers are traditionally used to measure these minute changes in gravity. In the area of oilfield investigation and earth formation characterization, accelerometers may be deployed in wireline applications, logging while drilling applications, or using coiled tubing.
U.S. Pat. No. 5,903,349 to Vohra et al. (the '349 patent) discloses a high performance optical fiber accelerometers using a flexural disc. While this accelerometer has many useful applications, its performance deteriorates in high temperature environments (above 70 degrees Celsius), such as that found in oilfield applications.
Accordingly, it is one object of the present invention to provide an apparatus and method of manufacturing the same to allow high temperature operation.